Apparatus and method for forming and mounting damper bars on grids



June 23, 1953 E. F. NICKL 2,642,648

APPARATUS AND METHOD FOR FORMING AND MOUNTING DAMPER BARS ON GRIDS Filed Aug. 51, 1949 ISnventor I! I v Patented June 23, 1953 Edwin F, Nick], Cedar Grove, N; assignor to I Radio Corporation of America, a corporation of Delaware Application August 31, 1949",-seri 1'1%.113347' 14 Claims. (01. air-25.17)

The present invention relates to an apparatus and method for forming and mounting damper bars from continuous stock in electron discharge devices and more particularly to an apparatus and method for mounting a damper bar on a grid structure having side rods with grid wire thereon.

Damper bars find wide use, in electron discharge devices for dampening the vibration of filamentary cathodes to improve operation of the device by reducingmicrophonics in the output thereof. Some damper bars comprise a straight wire having an insulated portion for engaging the filamentary cathode at a location and method rci improving the adherence damper bar to a support.

Another object is to provide an apparatus and method for simultaneously'cutting a damper bar" from a continuous supply and forming the cut end of the 'bar' for improved adherence to" a support r I 1 Another object is to provide an "apparatus; for automatically ositioning a support str cture in an appropriately predetermined manner and feedingla damper b'arto engage a; critical por onof the support structure without damage to other components of the structure. 7 further object is' to provide an apparatus intermediate its ends for deflecting it laterally; 15 for automatically positioning awoundf grid and and bare end portions for fixing to supports. a damper bar in appropriate relation so that Where wound type grids are employed-in the the damper bari engages portions of the 'grid device this for'm'of damper bar is usually disside rods intermediate the grid turns thereon. posed transversely of' the grid side rods and is Another objectis to provide an apparatus for fixed to one or both of 'the side rods. feeding a continuous damper bar stock, appro- The operation of mounting a damper baron parately positioning a wound grid" for receiving a WOUIld grid or a grid having side rods with a predetermined length of said stock and simulgrid wire disposed transversely thereof has heretaneously severing surplus stool; from the damper tofore involved a delicate manual operation bar and bending the severed end of the bar which has been rendered difficult because of partly arou a r e rod d Welding the the necessity for accomplishing the fixing of the bar to the side rods without interfering with the gridwire or'wires also fixed thereto. Since the manual operation of mounting a damper bar of the type described. asheretofore involved critical considerations of appropriate position of the bar longitudinally of the grid," suitable engagement of the grid side rods at a portion thereof intermediate two adjacent grid turns, and effectively welding or otherwise fixing the damper bar tothe grid side rods without damage to the grid, this operation has heretofore required'a relatively long time for accomplishment and has consequently increased the cost of manufacture while subject to the usuallimitations of handoperations'. Moreover, prior practices' have required the cutting of the damper bar to size and removal of a portion of the insulation therefrom prior to the mounting operation to render it suitable for welding vto the grid.

Accordingly it is an object ofthe invention to provide an apparatus-and method for automatically mounting a. straight damper 1 bar in an electron discharge device in a more expeditious and accurate manner.

Another object is to automatically and ac.- curately mount a damper bar on a Woundtype grid from a supply of continuous. coated wire; A further object is-to provide anapparatus bent end'of the bar around the grid side rod.

A further object is to provide an apparatus for automatically removing the insulation from a stock of insulated wire at predetermined longitudinal portions thereof and fixing predeter mined lengths of the stock so treated to a support. 7 According to the invention, an apparatus is provided including a plurality of means disposed in tandem array to support a grid having side rods, conditiondamper bar wire stock by removal of part of the insulation therefrom, feed the conditioned wire transversely of the grid side. rods and between two turns. of the grid, cut and form a desire'dlength of damper bar, and weld 'thecut and" formed damper bar to at wastone of the grid side rods. According tothe method of the invention a damper bar having bare end portions" and an intermediate coated portion is provided by removing a part of the insulation from a continuous supply of insulated wire, feeding'the wire so treated to a grid, sub'-.

sequently severing the wire to'for'ni a damper bar and at the same time forming one e'nd of the barto improve a weld between said end and one-of the grid side rods. g

Further objects and features of the invention will manifest themselves as thepresent description continues.

Referring'to'the drawing: p ,Figures 1, 2; 3', 4 and 5 each represent a sec 3 tional elevation of the apparatus of the invention, each figure showing the apparatus in a difierent position.

Thus Figure 1 shows the apparatus in the position of removing a portion of the insulation from damper bar stock and prior to a feeding of the damper bar stock to a grid;

Figure 2 shows the grid rotated so that the side rods are in position for receiving the damper bar stock therebetween; 1

Figure 3 is a view of the apparatus after the feeding operation; 7

Figure 4 shows the feeding carriage and insulation removal members moved to engage a fresh length of damper bar stock and the engagement by the welding electrodes of a grid side rod and a portion of the damper bar stock;

and

Figure 5 is a view of the cutters moved into position for cutting and bending a portion of the damper bar partly around a grid side rod,

bar stock, the operations of the apparatus are wholly automatic.

' The damper barstock comprises a continuous length of wire In having an insulating coatin H fed from a suitable supply which may be supported on a spool, not shown.

A straight damper bar when ultimately mounted in an electron discharge device includes bare ends, one or both of which may be fixed to spaced supports such as grid side rods. The intermediate portion of the damper bar is provided with an insulating coating for engaging a filamentary cathode to prevent shorts between the cathode and the support structure for the damper bar.

The first operation performed by the apparatus of "the invention is to remove the insulation from predetermined longitudinal portions of the coated stock. To this end the apparatus is provided with a pair of hammers, I2, 13 having fiat opposing surfaces. As the hammers l2, [3 are caused to approach each other by a power means, not shown, of relatively great force, an impact between said surfaces of the hammers results in a cracking off of the insulation on the portion of the stock between the hammers. This hammering action preferably involves the application of a single blow to the wire which, when accompanied by sumcient force will serve to crack the insulation and cause the same to fall from the wire. A jet of air, not shown, may be employed to complete the removal of the cracked insulating material. At the conclusion of the blow referred to the hammers l2, l3 will extend through the insulation I l and firmly engage the bar wire Ill. 7

The next operation of the apparatus is to feed the stock having part of its insulating coating removed, as indicated above, to a station where damper bars are cut from the stock and fixed damper bar stock and in the order named are viewed in Figure 1 to assume the position shown 7 spaced cutters l5, l6 and spaced welding electrodes I1, 13. Also supported in registry with said path is a'gridcomprising grid side rods 20, 2| and grid turns or wires 22, and oriented so as to cause the grid to extend transversely of to move by means, not shown, to the left as the path of travel of the damper bar stock and with said path disposed between two adjacent turns or wires of the grid. A mandrel l9 serves to support thegrid. This mandreldoes not extend into the path of travel of the damper bar stock.

The mandrel I9 is mounted for rotation on an axis longitudinal of the grid. Thus, before the damper bar stock is caused to move to the left beyond the cutters [5, i6 and towards the grid, the mandrel I9 is rotated clockwise by means, not shown, to provide clearance between the grid side rods and the damper bar stock as shown in Figure 2. The mandrel I9 is further provided with means,not shown, for receiving thereon a predeterminedlongitudinal portion of the grid to permit free entry of the damper bar stock between two adjacent transverse wires or turns of the grid. 7

After the damper bar stock extended across the grid side rods 20, 21 with the bare'wire portions opposite the grid side rods, the mandrel I9 is caused to rotate counterclockwise to bring the side rods firmly against the barewire portions of the damper bar'stock as viewed in Figure 3.

l8 are caused to approach each other by means,

not shown, to firmly engage grid side rod 20 and a bare portion of the damper bar stock, to fur ther restrain the portion of the damper bar stock fed to the grid against movement. Under this condition, as shown in Figure 4, the carriage I4 and the spreadhammers 12, I3 move to the right to engage a fresh section of damper bar stock.

The movement referred to of the carriage l4 and the hammers [2, I3 is incapable of disturbing the position of the damper bar section engaged by the grid side rods and the welding electrodes. With a portion of the damper bar stock therefore properly oriented and held against the grid side rods with the bare portions of the damper bar engaging the'side rods, cutters l5,

I6 are brought into action to cut the damper bar stock at a middle portion of therexposed wire adjacent the grid side rod 20 which is closer to the supply of damper bar stock than side rod 2|. The upper cutter I5 is formed with a bevelled cutting edge so disposed that a downward movement thereof towards the lower cutter 16, results in a severing 'of the damper bar stock to provide a damper bar engaging the side rods of the grid and'also in a bending of a portion of the cut end of the damper bar partly around grid side rod 20. This bending of the damper bar increases the area of surface contact between the damper bar and side rod 20. This increased surface contact, as shown in Figure 5,

Subsequently the welding electrodes 17,

permits more welding currenttotraverse; the parts to bewelded, resulting in an, improved weld;

It willv benoted thatthe faces of the welding electrodes l1, 18 have oppositelyinclined surfaces 23, 24. This inclination is provided. to permit the electrodes to engage only one side rod 20 and one end only of the damper bar, leaving side rod 2| and the other end of the damper bar free. By engaging only oneside rod-and one end of the damper bar, the welding electrodes produce a minimum of strain on the grid-on which the damper bar is mounted.

My apparatus is automatic-in operation except for the initial removal of the coating from the leading end of a fresh supply of damper bar stock and except for placement. of a grid on themam drel l9.

When a fresh supply of fully coateddamper bar stock is used, it isv necessary to. either. manually remove the coating at the leading end portion of. the wireto provide an uncoatedend: portion of a damper bar, or to feed the completely coated wire through the apparatus. with. a grid emitted therefrom during the first several cycles. of operation. The function of the first several cycles in this event would be to. remove coating from the leading end portion of the damper bar stock and cut the stock to provide the uncoated end portion having a suitable length required for finished damper bar.

If the first several cycles of the apparatus are utilized to provide a properly uncoated end portion of a damper bar the leading end of the uncoated stock should be. manually disposed between the hammers 12, I3 so that the stock extends at least one half of the distance through the hammers. This will provide a desired uncoated portion which is subsequently cut during a following cycle to appropriate length.

Since no grid is carried by the mandrel [9-, during the first several stock conditioning cycles referred to, the piece of wire severed during the cutting step readily falls from the electrodes without involving any weldin current. I The welding electrodes l1, I8 are fixed to movable supports, not shown, that limit the movement of the electrodes towards each other. i This move ment is limited to the extent that the closest the electrodes can approach each other involves a spacing between them that is slightly less than the spacing represented by the thickness of a grid side rod added to the thickness of an uncoated portion of the damper bar stock. The thickness of the uncoated damper bar portion therefore by itself is insufiicient to bridge the spacing between the electrodes when the latter are brought together as closely as the apparatus will permit, with the result that during the stock conditioning cycles no weldingaction'takes place.

-It will be noted that several cycles of the apparatus are required for the provision 'of a suitable uncoated end. portion of the initial damper bar produced. This. is for the reason. that the feed carriage l4 hasan. appreciable, length for support and feed purposes. Thus, at the end ofthe first cycle the leading end of the damper bar stock will be disposed somewhere along the line represented by the uncoated portion 1.0a shown, in Figurev 5. At the end. of. the second cycle the leading end will be. located along the, line of the uncoated. portion lflb, also shown in Figure 5. At the end of the thirdv cycle the lead-; ing end will. be disposed in the'path, of the cutters, l5, l6 and cut to appropriate. length... Therefore, the grid should not be mounted on the 6 mandrel IB -until'the beginning of theiourth cycle of'ope-ration ofthe apparatus, which condition is show-n in Figure 1. Beginning with the fourth cycle,- therefore, the feeding of a properly uncoated damper bar stock to the grid is fully automatic.

It a is thus apparent that with. the exception of placing thegrid on the mandrel I 9- and inserting the damper barstock between the hammers I2, [3 my novel apparatus is fully automatic.

Other-readily apparent advantages of my novel apparatus are as follows: The position of the damper bar on the grid is controlled mechanically so that an accurate disposition ofthe damper bar between the grid turns is assured. thus, eliminating the hazard of damage to the grid. The accurate mechanical control afforded by my apparatus also assures a proper engages ment between the uncoated portions of the damper bar and grid side rods, which results in a desired orientation of the coated portion of the damper bar withv respect to a filamentary cathode to be damped. A further and overall advantage of my apparatus is a reduction in the time required for mounting a damper bar onawound grid, thus contributing to a reduction in the cost of manufacture of electron discharge devices in which damper bars are required. The advantages of my novel apparatus are particu larly significant. in the manufacture of" miniatin'e i type tubes in which the mounting of a damper bar by manual means is extremely difficult and time consuming.

The elements of my apparatus shown and described herein are to be regarded merely as an illustrative embodiment of my invention. Various modifications maybe made in the structure ofthese elements as will be apparent to persons skilled in the pertinent art without departing from the spirit of the invention and it is consequently desired that such modifications be in eluded within the scope of the invention as pointed out in the appended claims. I

I claim:

1. Apparatus for forming and mounting a straight damper bar on a grid from continuous stock of coated damper bar material; comprising impact meansfor removing the coating from aportion of said damper bar material and for engaging the resultant bare portion for-feeding said stock in intermittent steps through a predeter mined path, 'a grid support spaced from saidmeans for supporting said grid transversely of" V said path for receiving said stock across a pro-- determined transverse portion of said grid, means for severing said stock between said first named-- means and said grip support to provide astraight' damper bar and means. for fixing said dampen bar to said grid.

2. A paratus for'mounting a straight dam-per bar on a grid having two side rods to engage op-'- posite sides of said side rods, comprising means for intermittently feeding straight damper bar stock in-apredetermined path, means for sup-- portinga wound grid transversely of said path for receiving said stock between two adjacent turns thereof and with said stock engaging opposite sides ofsaid side rods, means for cutting said stock adjacent one of said siderods to; provi-dea damper bar and for bending said damper bar partly around said one of said side rods, and means for fixing said damper barto" onexofsaid side rods. 7 I n} .3; Apparatus for making; adamperbar from continuous coated stock' and for mounting the 7 damper bar on a grid having two side rods, comprising-impact means for removing arportion of the coating on said stock and for firmly engaging the resultant bared portion thereof, said impact means being movable in a path longitudinal of said stock when engaging said stock, a grid support for supporting a wound grid for receiving a predetermined length of damper bar stock fromsaid impact means between two adjacent turns of the grid and between said side rods, cutting and forming means between said impact means and, said grid support for severing a predetermined length of said stock to provide a damper bar and for bending a portion of said damper bar partly around one of said side rods, and welding electrodes disposed on opposite sides of said one of said side rods for fixing the bent portion of said damper bar to said last mentioned side rod.

'4. Apparatus for mounting a dampercbarron a grid having grid turns supported on two: side rods from a continuous supply of coated damper bar stock comprising impact means for uncoating portions of said stock and feeding the stock in a predetermined path, means for supporting the grid for receiving a portion of said stock between two adjacent turns thereof with one of said uncoated portions engaging one of said side rods, means for supporting one side of said last named side rods, movable cutting means having a beveled edge for cutting said stock adjacent said side rod and approaching from the other side of said side rod for providing a damper bar of predetermined length and for bending a portion of said damper bar partly around said side rod to increase the area of surface contact therebetween, and means for welding said bent portion of said damper bar to said side rod for fixing the damper bar on said grid.

i 5. Apparatus for mounting a damper bar from continuous coated stock on a grid having grid turns thereon and side rods comprising means for removing the coating from predetermined longitudinal portions of said stock and moving said stock longitudinally, means for supporting and guiding the stock so uncoated to a mounting station, rotatable means at said mounting station for supporting said grid with the space between two adjacent turns in registry with the path of movement of said stock, whereby said grid is rotatable on its longitudinal axis for moving said side rods out of-the path of movement of said stock; meansadjacent said grid support for cutting said stock to. provide a damper bar of predetermined length, said means having a formingsurface for bending an end portion of said damper bar partly around one of said grid side rods, and means for fixing said bent portion of said damper bar to said one of said side rods.

6, Apparatus for mounting a damper bar of predetermined length and having bare end por tions and an intermediate coated portionson a grid having two side rods and turns of grid wire: thereon toengage one side'of'one of said side rods and the opposite sideof the other of said rods, comprising hammers for receiving eo'ntinuous stock ,ofcoated damper bar material and removing said coating from spaced longitudinal portions of'said material, said hammers also serving to move said damper bar material longitudinally, additional means for guiding'damper barmaterialfed to it by said hammersin a pre-;

determined path, means for supporting said grid transversely of said path with two adjacent turns on-oppositesides of said path, a combined;

7. Apparatus for mounting a damper bar on a grid having two side .rods and transverse wires supported thereon from a continuous supply of, coated damper bar-stock, comprising means for removing the coating from longitudinal portions of said stock to provide bare end portions of said damper bar, means for feeding said partly uncoated stock in steps for a distance equal to the length of a damper bar and in a predetermined path, means for supporting said grid transversely of said path with two adjacent transverse wires andthe two side rods thereof disposedon' different sides of said path, said supporting means being rotatable for causing said side rods to firmly engage opposite sides of said damper,

bar, means in said path between said feeding means and said supporting means for severing from said stock a predetermined length thereof to provide a damper bar, and means for fixing said damper bar to at least one of said side rods. 8. Apparatus for making a damper bar having a metallic core and an insulating coating thereon a continuous supply of damper bar stock and feeding said stock in intermittent steps in a predetermined path, means for supporting said grid transversely of said path with the space between two adjacent turns thereof and between said side rods in registry with said path, said last named means being rotatable to cause said side rods to engage opposite sides of said damper bar stock at bared portions thereof, welding electrodes movable to press one of'said bared portions against one of said side rods for restraining movement of said damper bar stock, said first-named means being retractable to engage a fresh portion of damper bar stockwhile said stock is held by said electrodes, and means for severing the portion of said stock engaging said side'rods to provide a damper bar, and bending an end thereof partly around one of the grid side rods to increase the area of surface contact therebetween, said'welding electrodes being adapted to weld'the bent portion of said damper bar to at least one of said grid side rods.-

9. Apparatus for making aestraight; damperv I bar from coated continuou stoclrand mounting the same on a wire grid; comprising opposed hammers being held together and movable lon-,

gitudinally of said stock to carry said stock a predetermined distance, means for supporting said grid for receiving transversely thereof and,

between two adjacent wires thereon a portion.

of said damper bar stock, mean for severing said portion from the remainder of'sai'd stock,

and means for fixing said damper bar to said grid.

10. Method of mounting a straight damper bar having bare end portions and an intermediate insulatingly coated portion, on a grid having a side rod and turns on said rod, comprising the steps of hammering a predetermined portion of a continuous stock of damper bar material for removing the insulation thereon, feeding the continuous stock transversely of the grid and between two adjacent turns thereof adjacent said side rod, holding said stock firmly against said side rod, cutting said stock adjacent said side rod to provide a damper bar, and fixing said damper bar to said rod.

11. Apparatus for mounting a straight damper bar from continuous coated stock thereof on a grid having at least one side support rod, comprising combined coating removing and stock gripping means, said means comprising two oppositely disposed and movable members, said members being adapted to receive said stock therebetween and being movable towards each other for engaging a portion of said stock with appreciable impact, whereby the coating on said portion is removed and a resultant bare portion of the stock is engaged by said members, said members being movable while engaging said stock in a direction axially of the stock, means for supporting said grid transversely of said direction, means movable with said members for guiding said stock to said grid and adjacent said at least one side support rod, welding electrodes adapted to hold said support rod against movement and to provide an anvil, a first cutter spaced from said welding electrodes and adapted to provide another anvil, a second and movable cutter mounted in opposed relation to said first cutter and between said first cutter and said welding electrodes, said second cutter having a bevelled end to provide a relatively sharp edge adjacent said first cutter and a relatively blunt edge adjacent said welding electrodes, whereby said second cutter is adapted to first out said stock to provide a damper bar and then to partly wrap the cut end portion of the damper bar around said support rod.

12. Method of making an electron tube subassembly comprising a grid having a support rod and a straight damper havinga coated intermediate portion and an uncoated end portion fixed to said support rod, including the steps of hammering a, predetermined portion of said stock to remove the coating therefrom to provide a bare portion, feeding said hammered stock into transverse engagement between said bare portion thereof and said support rod, simultaneously severing said stock and wrapping said bare portion at least partly around said support rod to provide increased contact area therebetween, and welding said severed and wrapped bare portion to said support rod.

13. Apparatus for mounting a straight damper bar on a grid having two side rods to engage opposite sides of said side rods, comprising means for intermittently feeding straight damper bar stock in a predetermined path, means for supporting a wound grid transversely of said path for receiving said stock between two adjacent turns thereof and with said stock engaging opposite sides of said side rods, means for cutting said stock adjacent one of said side rods to provide a damper bar, and means for fixing said damper bar to one of said side rods.

14. Apparatus for mounting a straight damper bar on a grid having two side rods, comprising means for supporting said grid with said side rods thereof lying in a predetermined plane, means for feeding a straight damper having uncoated ends and an intermediate coated portion, in a plane angularly disposed with respect to said firstnamed plane, means for bending one of said uncoated ends partly around one of said side rods for increasing the contact area therebetween and for urging the other end of said damper bar against the other of said side rods, and means for welding said one of said ends of the damper 1 bar to said one of said side rods.

EDWIN F. NICKL.

, References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,947,449 Anderson et a1. Feb. 20, 1934 2,329,769 Kinyon Sept. 21, 1943 

